* [PATCH] nilfs2: propagate directory read errors from nilfs_find_entry()
[not found] <66f59678.050a0220.46d20.0001.GAE@google.com>
2024-09-28 3:53 ` [syzbot] [serial?] INFO: task hung in vcs_open (8) Ryusuke Konishi
@ 2024-10-04 3:35 ` Ryusuke Konishi
1 sibling, 0 replies; 2+ messages in thread
From: Ryusuke Konishi @ 2024-10-04 3:35 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-nilfs, syzbot, syzkaller-bugs, LKML, Lizhi Xu
Syzbot reported that a task hang occurs in vcs_open() during a fuzzing
test for nilfs2.
The root cause of this problem is that in nilfs_find_entry(), which
searches for directory entries, ignores errors when loading a
directory page/folio via nilfs_get_folio() fails.
If the filesystem images is corrupted, and the i_size of the directory
inode is large, and the directory page/folio is successfully read but
fails the sanity check, for example when it is zero-filled,
nilfs_check_folio() may continue to spit out error messages in bursts.
Fix this issue by propagating the error to the callers when loading a
page/folio fails in nilfs_find_entry().
The current interface of nilfs_find_entry() and its callers is
outdated and cannot propagate error codes such as -EIO and -ENOMEM
returned via nilfs_find_entry(), so fix it together.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: Lizhi Xu <lizhi.xu@windriver.com>
Closes: https://lkml.kernel.org/r/20240927013806.3577931-1-lizhi.xu@windriver.com
Reported-by: syzbot+8a192e8d090fa9a31135@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8a192e8d090fa9a31135
Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations")
Cc: stable@vger.kernel.org
---
Hi Andrew, please apply this as a bug fix.
This fixes a flaw in nilfs2's directory lookup error handling that was
the root cause of the vcs hang issue recently reported by syzbot.
Thanks,
Ryusuke Konishi
fs/nilfs2/dir.c | 48 ++++++++++++++++++++++++-----------------------
fs/nilfs2/namei.c | 39 +++++++++++++++++++++++++-------------
fs/nilfs2/nilfs.h | 2 +-
3 files changed, 52 insertions(+), 37 deletions(-)
diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c
index fe5b1a30c509..a8602729586a 100644
--- a/fs/nilfs2/dir.c
+++ b/fs/nilfs2/dir.c
@@ -289,7 +289,7 @@ static int nilfs_readdir(struct file *file, struct dir_context *ctx)
* The folio is mapped and unlocked. When the caller is finished with
* the entry, it should call folio_release_kmap().
*
- * On failure, returns NULL and the caller should ignore foliop.
+ * On failure, returns an error pointer and the caller should ignore foliop.
*/
struct nilfs_dir_entry *nilfs_find_entry(struct inode *dir,
const struct qstr *qstr, struct folio **foliop)
@@ -312,22 +312,24 @@ struct nilfs_dir_entry *nilfs_find_entry(struct inode *dir,
do {
char *kaddr = nilfs_get_folio(dir, n, foliop);
- if (!IS_ERR(kaddr)) {
- de = (struct nilfs_dir_entry *)kaddr;
- kaddr += nilfs_last_byte(dir, n) - reclen;
- while ((char *) de <= kaddr) {
- if (de->rec_len == 0) {
- nilfs_error(dir->i_sb,
- "zero-length directory entry");
- folio_release_kmap(*foliop, kaddr);
- goto out;
- }
- if (nilfs_match(namelen, name, de))
- goto found;
- de = nilfs_next_entry(de);
+ if (IS_ERR(kaddr))
+ return ERR_CAST(kaddr);
+
+ de = (struct nilfs_dir_entry *)kaddr;
+ kaddr += nilfs_last_byte(dir, n) - reclen;
+ while ((char *)de <= kaddr) {
+ if (de->rec_len == 0) {
+ nilfs_error(dir->i_sb,
+ "zero-length directory entry");
+ folio_release_kmap(*foliop, kaddr);
+ goto out;
}
- folio_release_kmap(*foliop, kaddr);
+ if (nilfs_match(namelen, name, de))
+ goto found;
+ de = nilfs_next_entry(de);
}
+ folio_release_kmap(*foliop, kaddr);
+
if (++n >= npages)
n = 0;
/* next folio is past the blocks we've got */
@@ -340,7 +342,7 @@ struct nilfs_dir_entry *nilfs_find_entry(struct inode *dir,
}
} while (n != start);
out:
- return NULL;
+ return ERR_PTR(-ENOENT);
found:
ei->i_dir_start_lookup = n;
@@ -384,18 +386,18 @@ struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct folio **foliop)
return NULL;
}
-ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
+int nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr, ino_t *ino)
{
- ino_t res = 0;
struct nilfs_dir_entry *de;
struct folio *folio;
de = nilfs_find_entry(dir, qstr, &folio);
- if (de) {
- res = le64_to_cpu(de->inode);
- folio_release_kmap(folio, de);
- }
- return res;
+ if (IS_ERR(de))
+ return PTR_ERR(de);
+
+ *ino = le64_to_cpu(de->inode);
+ folio_release_kmap(folio, de);
+ return 0;
}
void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index c950139db6ef..4905063790c5 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -55,12 +55,20 @@ nilfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
struct inode *inode;
ino_t ino;
+ int res;
if (dentry->d_name.len > NILFS_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);
- ino = nilfs_inode_by_name(dir, &dentry->d_name);
- inode = ino ? nilfs_iget(dir->i_sb, NILFS_I(dir)->i_root, ino) : NULL;
+ res = nilfs_inode_by_name(dir, &dentry->d_name, &ino);
+ if (res) {
+ if (res != -ENOENT)
+ return ERR_PTR(res);
+ inode = NULL;
+ } else {
+ inode = nilfs_iget(dir->i_sb, NILFS_I(dir)->i_root, ino);
+ }
+
return d_splice_alias(inode, dentry);
}
@@ -263,10 +271,11 @@ static int nilfs_do_unlink(struct inode *dir, struct dentry *dentry)
struct folio *folio;
int err;
- err = -ENOENT;
de = nilfs_find_entry(dir, &dentry->d_name, &folio);
- if (!de)
+ if (IS_ERR(de)) {
+ err = PTR_ERR(de);
goto out;
+ }
inode = d_inode(dentry);
err = -EIO;
@@ -362,10 +371,11 @@ static int nilfs_rename(struct mnt_idmap *idmap,
if (unlikely(err))
return err;
- err = -ENOENT;
old_de = nilfs_find_entry(old_dir, &old_dentry->d_name, &old_folio);
- if (!old_de)
+ if (IS_ERR(old_de)) {
+ err = PTR_ERR(old_de);
goto out;
+ }
if (S_ISDIR(old_inode->i_mode)) {
err = -EIO;
@@ -382,10 +392,12 @@ static int nilfs_rename(struct mnt_idmap *idmap,
if (dir_de && !nilfs_empty_dir(new_inode))
goto out_dir;
- err = -ENOENT;
- new_de = nilfs_find_entry(new_dir, &new_dentry->d_name, &new_folio);
- if (!new_de)
+ new_de = nilfs_find_entry(new_dir, &new_dentry->d_name,
+ &new_folio);
+ if (IS_ERR(new_de)) {
+ err = PTR_ERR(new_de);
goto out_dir;
+ }
nilfs_set_link(new_dir, new_de, new_folio, old_inode);
folio_release_kmap(new_folio, new_de);
nilfs_mark_inode_dirty(new_dir);
@@ -440,12 +452,13 @@ static int nilfs_rename(struct mnt_idmap *idmap,
*/
static struct dentry *nilfs_get_parent(struct dentry *child)
{
- unsigned long ino;
+ ino_t ino;
+ int res;
struct nilfs_root *root;
- ino = nilfs_inode_by_name(d_inode(child), &dotdot_name);
- if (!ino)
- return ERR_PTR(-ENOENT);
+ res = nilfs_inode_by_name(d_inode(child), &dotdot_name, &ino);
+ if (res)
+ return ERR_PTR(res);
root = NILFS_I(d_inode(child))->i_root;
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index fb1c4c5bae7c..45d03826eaf1 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -254,7 +254,7 @@ static inline __u32 nilfs_mask_flags(umode_t mode, __u32 flags)
/* dir.c */
int nilfs_add_link(struct dentry *, struct inode *);
-ino_t nilfs_inode_by_name(struct inode *, const struct qstr *);
+int nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr, ino_t *ino);
int nilfs_make_empty(struct inode *, struct inode *);
struct nilfs_dir_entry *nilfs_find_entry(struct inode *, const struct qstr *,
struct folio **);
--
2.43.0
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